Pinacol → 2-(4-Bromobutyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane

HRID 579475Notes

Reaction equation

HRID 579475 reaction equation
[B:1]1([CH2:10][CH2:11][CH2:12][CH2:13][Br:14])OC2C(=CC=CC=2)O1.[OH:15][C:16]([C:19]([OH:22])([CH3:21])[CH3:20])([CH3:18])[CH3:17]>C1COCC1>[Br:14][CH2:13][CH2:12][CH2:11][CH2:10][B:1]1[O:22][C:19]([CH3:21])([CH3:20])[C:16]([CH3:18])([CH3:17])[O:15]1

Participants

4

Reactant 2

HCID 6425PinacolHCID 35636154-Bromo-1-butylboronic acid catechol ester

Product 1

HCID 111963112-(4-Bromobutyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolaneYield 97.4%

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent

Procedure

After gently warming until melted, 4-bromo-1-butylboronic acid catechol ester (112.2 g, 0.44 mol, 1.0 equiv), while under a stream of nitrogen, was added to a 3-necked 500 mL round-bottomed flask, diluted with freshly distilled THF (150 mL, 3.0 M) and treated with pinacol (104.0 g, 0.88 mol, 2 equiv) in one portion. After stirring for 16 h under a nitrogen atmosphere the resulting solution was concentrated. The crude product was diluted with heptane (500 mL) and cooled in an ice-water bath. After 1 h, the precipitated catechol was removed by filtration and the remaining solution was filtered through a short pad of silica gel (500 g) wetted with heptane. After eluting with solutions of 5% ethyl acetate in heptane (700 mL) and 10% ethyl acetate in heptane (700 mL), the filtrate was concentrated to give 2-(4-bromobutyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane as a colorless oil (112.7 g, 97%). 1H NMR (CDCl3, 300 MHz) δ 3.38 (t, J=6.6 Hz, 2H), 1.90-1.78 (m, 2H), 1.58-1.44 (m, 2H), 1.26 (s, 12H), 0.78 (t, J=7.5 Hz, 2H); ESI-LCMS m/z calcd for C10H20BBrO2: expected 262.1. found 263.1 (M+H)+.

Workup

  1. temperatureAfter gently warming
  2. concentrationwas concentrated
  3. additionThe crude product was diluted with heptane (500 mL)
  4. temperaturecooled in an ice-water bath
  5. waitAfter 1 h
  6. customthe precipitated catechol was removed by filtration
  7. filtrationthe remaining solution was filtered through a short pad of silica gel (500 g)
  8. washAfter eluting with solutions of 5% ethyl acetate in heptane (700 mL) and 10% ethyl acetate in heptane (700 mL)
  9. concentrationthe filtrate was concentrated

Sources & evidence

ORD record
ord-8836b3fc0406449788bc19168938be41
Source dataset
uspto-grants-2015_05
Patent number
US09040703B2

Reaction notes

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